strange steering "shimmy" issue

[keakar]

my 06 4r sport has an issue with a steering vibration as though it has a tire out of balance. the tires are fairly new low mileage wranglers.

it only happens around 60-70 mph and its not a big vibration but just a slight shimmy in the steering wheel.

i checked the front end parts and its in alignment because i can let go of the steering wheel and it keeps goes straight without veering off in any direction.
nothing is lose or worn that i can find, the tires and rims were removed and checked for balance or bent rims and i did a 4 wheel all new pads and rotors brake job. i flushed out the power steering system and reservoir and put all new fluid and steering wheel feels tight with instant response and no play.

i even had the tires rotated front to back when they were rebalanced. the balancing was needed as all 4 tires were off quite a bit and that reduced the shimmy, but it didnt eliminate it.

i bought it with 150k miles and dont know much about its history other then it was a corporate company vehicle that got most of its miles on the highway.

no history or record of ever having been in an accident and other then the back glass being replaced (it had a small identification letter mark on it like things you get from a salvage yard) , i dont think it ever had anything done to it other then routine maint.

my only guess is an out of balance drive shaft, but the only way i can image this happening is, im wondering is if the u-joint was replaced and the yoke got flipped while doing it? would that be easy to tell just by looking at it? and would it be causing such a small vibration if that happened?

i dont really have any money for paying for diagnosing this at a shop and being told they cant find the problem or want to start randomly replacing things as most shops tend to do to make money.

im lost as what could be the problem.

 

[ElZilcho]

It doesn't sound like a U-joint/driveshaft to me. They usually "shimmy" (10 Hz) around 10-20 MPH because they are turning about 4 times faster than the tires and by 60 MPH it has settled out to a "hum" (40 Hz) or vibration (or completely flown apart, (No Hz)). You would also feel it in the seat (and maybe see it in the reflection of your mirrors). An out-of-phase U-Joint would buck hard and at really low speed. It would also be more effected by axle articulation than speed, and that's not an issue for the front shaft on an IFS truck.

My guess, if you only feel it in the wheel, and not the chassis...it's somewhere in the un-sprung rotational mass of the front of the truck. Wheel, tire, rotor, etc. Most likely it's excessive run-out on one (or more) tires. Lots of tire shops balance truck tires to the same standards as car tires but the forces acting on an out-of-balance tire increase as a square of the radius so a slightly larger tire has WAY more inertia than a smaller tire. I would take it to get road force balanced. I don't know your tire shop but they probably just kept adding more weight to balance them instead of rotating the tire on the wheel to match high/low spots. Before you spend more money though, there are couple of things you can test.

In order of ease, but reverse order of liklihood:

First, jack up the front of the truck, take off both wheels and turn the hubs by hand (wrench, stick, pipe) feeling for a detent in the bearing or listening for noise. It's probably not a bearing but it's an easy test. Second... if you have the time (and patience) rotate your tires again. You said it changed when you rotated them the first time. This time rotate only one side front to back and check the vibration. Then try the other side... Then cross-wise... Then the other cross-wise... Then left to right...

...you get the idea. If it changes at any point you've isolated it to the wheel/tires. Hell even if you make it worse you've made it easier for a tech to find!

I'm no expert, but that's my two cents. Good Luck!

 

[keakar]

In order of ease, but reverse order of liklihood:

First, jack up the front of the truck, take off both wheels and turn the hubs by hand (wrench, stick, pipe) feeling for a detent in the bearing or listening for noise. It's probably not a bearing but it's an easy test. Second... if you have the time (and patience) rotate your tires again. You said it changed when you rotated them the first time. This time rotate only one side front to back and check the vibration. Then try the other side... Then cross-wise... Then the other cross-wise... Then left to right...

...you get the idea. If it changes at any point you've isolated it to the wheel/tires. Hell even if you make it worse you've made it easier for a tech to find!

I'm no expert, but that's my two cents. Good Luck!

well it changed when the tires were rotated but i think only because all 4 tires were way way out of balance, im talking like 2-3 weights added to each rim, in one case 1 oz of weights had to be removed from a tire. so im putting that down in my mind as the cause of making a "difference". im guessing since it was a corporate vehicle, whoever put on the last set of tires left the weights on it and never rebalanced to tires. there was a "little" bit of shake to the seats but it disappeared after the balance and rotate and the tire guy was a friend so he new to watch for something not right like a bent rim or tire out of round, but admittedly its hard to tell by eye if a tire isnt right

the tire guy suggested it was just really cheap crappy tires and i hate to hear that because im poor and cant afford to replace tires unless there is a bigger issue then "maybe" causing a slight shimmy and they are literally almost new, so if that is the issue, then im stuck with these tires for another 4-5 years at least :redbrick:

since they are the stock oem mags im pretty sure its not a bent rim

 

[jdc62]

I had a similar problem a couple of years ago. I had the tires balance and rotated, changed the power steering fluid and even had the alignment and front suspension checked out by a dealer. Nothing helped and the technician found no issues. I finally checked the front brakes and found that a couple of pistons on the right front caliper were stuck. After replacing the caliper the problem went away. The odd thing was the truck tracked straight and handled perfectly fine before the fix. There was also no pull during braking.

Not sure that’s your problem but it’s worth checking into. Good luck.

 

[jrm]

4th gen 4runners require lug eccentric tire balancing

and cant be balanced using the common hub eccentric balancing method no matter how many times the guy trying to balance your tires tells you he can do it.

 

[ElZilcho]

I finally checked the front brakes and found that a couple of pistons on the right front caliper were stuck. After replacing the caliper the problem went away

There is a concurrent thread with similar symptoms and the owner traced it to a stuck caliper:

http://www.toyota-4runner.org/4th-gen-t4rs/250281-shuttering-while-driving.html

Sounds like a likely culprit. In the event it's not your gremlin.

admittedly its hard to tell by eye if a tire isnt right

I know I sound like a shill, but I would still get a road force balance. I don't think of Goodyear Wranglers as cheap tires but even quality tire manufacturers send out a dud every once in a while. I had a Michelin Pilot Super Sport that was 44lbs (yeah, pounds) out of round. All wheels and tires have some run-out and a competent tech on a road force machine will match high and low spots before adding any weight. They will also be able to tell you exactly how much run-out is in each wheel/tire combo. If there is a bad tire (and you bought them new) Goodyear will likely warranty it.

 

[BackOff]

I am going to lean towards a 'good' balance.
I had a bad shimmy at 50+ felt like a thrown wheel weight.
I swapped tires to a different set of rims, Still wonky.
Actually think one of the 5 tires I have is out of round and is making the bouncy/shimmy. And a bad passenger rear shock made it worse, dent in it from rock.
After I rotated my bad one to the 'spare' it went away...and the new shock might have helped some.

Killroy was here...

 

[hoodoo]

I am going to lean towards a 'good' balance.
I had a bad shimmy at 50+ felt like a thrown wheel weight.
I swapped tires to a different set of rims, Still wonky.
Actually think one of the 5 tires I have is out of round and is making the bouncy/shimmy. And a bad passenger rear shock made it worse, dent in it from rock.
After I rotated my bad one to the 'spare' it went away...and the new shock might have helped some.

Killroy was here...

I also agree with a "good balance".

Also, an alignment person who knows what he/she are doing, can eliminate the problem if it is related to the tires/alignment. Most mechanics do the alignment to specs and out the door it goes. Get together with a GOOD alignment person and perhaps you will find joy.